Abstract/Summary The frequent exposure to chemicals in the environment, diet, endogenous electrophiles, and reactive oxygen species leads to the chemical modification of DNA, resulting in the formation of DNA adducts. Some DNA adducts can induce mutations during cell division, and when occurring in critical regions of the genome, can lead to disease, including cancer. The targeted analysis of DNA adducts over the past 30 years has revealed that the human genome contains a wide array of DNA adducts, many of which are attributed to life-style factors, such as smoking, the eating of well-done cooked meats, or through oxidative stress. With the advancement of high- resolution mass spectrometry instrumentation and new scanning technologies, untargeted ?omics? approaches have become available to simultaneously screen for multiple DNA adducts in a single assay. However, the development of this emerging field of DNA adductomics is hindered by the lack of a publicly available mass spectral database for DNA adduct identification and characterization. Our goal is to curate and develop a comprehensive database of DNA adducts standards, obtained from international collaborators and commercial sources. The database will be freely available and searchable by the public. In Aim 1, we will establish an extensive collection of DNA adduct standards, via our domestic and international collaborations and commercial sources. We will prioritize 2'-deoxyribonucleoside and nucleobase adducts formed from environmental and dietary toxicants, and endogenous electrophiles, but also acquire modified RNA adduct standards from the emerging field of RNA adductomics. We will collect high-resolution mass spectra of these adduct standards via two commonly used mass spectrometer platforms, Orbitrap MS and Q-TOF MS. Spectra of MS, MS2 and MS3 will be acquired at various collision energies to characterize adduct structures. In Aim 2, we will develop an automated workflow to process MS2 and MS3 data to rapidly curate the spectra of individual DNA adducts with annotation, which can be submitted to a repository using commonly available software. The resulting spectral library will be freely available for download in common formats for characterization of DNA adductome profiles by members of the research community. The successful establishment of a validated DNA adduct mass spectral database in a searchable, reference library is critical for the comprehensive analysis of DNA adductome profiles from cellular DNA, urine, and other biological matrices. This database will facilitate the usage of DNA adductomics in human cohort studies and advance our understanding of the relationships between external and internal exposures and disease risk.